1. Field of the Invention
The present invention relates to an image processing apparatus and an image pickup apparatus for processing plural pieces of image data obtained by continuous shooting etc.
2. Description of the Related Art
When image shooting is performed using a digital camera (image pickup apparatus) provided in a mobile telephone etc., the effect of camera shake occurs on an image to be taken by, for example, the hand holding the mobile telephone shakes during the exposure. To suppress the effect of the camera shake, a camera shake correction is made to a taken image.
In the camera shake correcting process, a combining process is performed on plural (N) pieces of image data taken by continuous shooting to obtain one combined image.
The following conventional methods are well known as the combining process.    (1) The first taken image is defined as a base image, and the second through N-th images are sequentially combined with the first base image.    (2) The m-th (for example, m=N/2) taken image is defined as a base image, and other images are sequentially combined with the m-th base image.
In the case of the method (1) above, the camera shake normally occurs in a certain direction. Therefore, as the first through N-th images are sequentially superposed, there occurs a larger shift between the first image (namely, the base image) and the last object image to be superposed, thereby degrading the superposing capability.
Furthermore, in the method (2) above, for example, when the m-th (m=N/2) taken image is a base image, it is expected that the amount of shift is about ½ as compared with the case where the first or N-th image is defined as a base image, thereby improving the superposing capability. However, since the m-th image is a base image for superposition, there occurs a time lag between the image taken at the point of pressing a shutter button and the image used as a base image when the images are superposed although the user considers that the image is taken when the user presses the shutter button. As a result, there occurs a larger shift from a user-desired image.
Various techniques are disclosed as camera shake correction technology.
For example, the patent document 1 discloses an electronic camera having two modes, that is, a blurring correction mode (shake correction mode) and a non-blurring correction mode (non-shake-correction mode). The electronic camera performs a blurring correction (shake correction) only during exposure of a CCD (charge coupled device) and does not perform the blurring correction during an output period of pixel data when the electronic camera is in the photographing preparation period (in the non-blurring correction mode).
The patent document 2 discloses a camera capable of controlling the operation speeds of a mirror and a shutter by changing them from those in the normal photographing mode when the shake prevented photographing mode is selected. A photographing mode selecting part of the camera selects the photographing mode of the camera such as the shake prevented photographing mode, the normal photographing mode, etc. A drive speed altering part outputs to a mirror driving part and a shutter driving part an instruction to change a drive speed of the mirror and the shutter at the start of the exposure on the basis of the selection result of the photographing mode selecting part.
[Patent Document 1] Japanese Published Patent Application No. 2003-333414 “Electronic Camera”
[Patent Document 2] Japanese Published Patent Application No. H7-28149 “Camera Shake Preventive Apparatus”